Method of coating articles



Jan. 17, 1933. cox 1,894,671

METHOD OF COATING ARTICLES Filed June 8, 1929 mvema/ 7/70/7745 /f. 60%

Patented Jan. 17, 1933 UNITED STATES PATENT OFFICE THOIAS KING COX, OFCHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COK- PANY, DVCORPORATED,OF NEW YORK, N. Y., A CORPORATION OF NEW YORK METHOD OF COATING ARTICLESApplication filed. Jnne'8, 1929. Serial No. 888,351.

This invention relates to a method of coating articles, and moreparticularly to a meth- 0d of treating wire to promote adherence theretoof an insulating coating.

An object of the invention is to provide a simple and efficient methodof treating articles to promote the adherence thereto of a coatingmaterial.

According to the general features of the invention, the article to becoated is subjected to a bath of an organic acid, and a coatmg ofinsulating compound is subsequently applied to the article. Due to theaction of the acid a firm bond is formed therebetween which issubstantially integral with both the coating and the article.

i The invention will be readily understood from the followingspecification when read in conjunction with the accompanying drawing, inwhich Fig. 1 is a fragmentary plan view of an apparatus which may beemployed in practicing the invention;

gig. 2 is a fragmentary elevation thereof, an

Fig. 3 is an enlarged cross sectional view of an insulated copper wireformed in accordance with the invention.

The apparatus shown consists of an extruding head 10 which is secured bybolts 11 to an insulation extruding machine 12 (shown broken away) ofany well known type, wherein the materials comprising the insulation aremacerated, heated, and mixed into a warm, homo eneous mass. A nozzle 14projects outwar ly from the extruding head 10 and is adapted to receiveat one end a tinned copper wire 15 travelling in a horizontal path and,as the wire passes from the other end of the nozzle, to extrude upon ita cylindrical coating 16 of insulating compound. Although tinned copperwire is referably used, the invention is also applicale to allsubstances which react with an organic acid to form salts soluble incoating materials such as hydrocarbons and .exudations. I Mounted uponthe extruding head 10 by bolts 17 in such manner as to be locatedbeneath the wire 15 before its passage into the nozzle 14 is a container18, composed gral projecting drain 20 having a bottom inclined to directinto the basin portion liquid deposited thereon. The basin portioncontains a supply of oleic acid 23 which saturates a sponge 24 restingtherein, the latter being of sufiicient size to protrude above the sidesof the container 18 and be maintained at all times in contact with themoving wire 15. The nozzle 14 is fitted at the receiving end thereofwith a gland 26 which is of such construction as will permit it to bearupon the periphery of the wire 15 and remove therefrom the excess ofacid, which drips into the drain. 20 and is thereby returned to the suply 23.

he insulating compound extruded uponv the wire may be composed; forexample, of

25% reclaimed rubber, 20% smoked sheet 7 ance with establishedpracticedependingupon 75 the character of insulation desired. It is essential,however, that the compound include a substantial proportion of asubstance which will dissolve metallic salts such as tin oleate.Examples of such materials, in addition to the compound described above,are gutta percha, paraflins, and other hydrocarbons, and certain mexudates useful as insulators, such as be ata. A

After treatment in accordance with the step described above, it has beenobserved that the wireupon receiving a deposition of insulating materialwill, upon subsequent vulcanization thereon of the insulating material,be found tobe securely bonded to such insulation. Although it isdiflicult to observe exactly the progress of the reactions producingthis bond, it is robably due to the fact that the action of t e acid uon the metal surface of the wire'forms a of salts of tin, or tin oleate.These salts, being soluble in the warm compound, create a film 27between .the metal and the com ound which is essentially integral withbot U on cooling after vulcanization the hon will be 1 found to resiststrongly strains such as would normally stri' insulation applied in theold method there rom.

In addition to oleic acid, advantageous results ma be secured by theuse, in lieu thereof, of other organic acids having a high molecularweight such as palmitic and stearic acids. It is also possible to employorganic acids having lower molecular weights, such as acetic acid andformic acid. In the latter cases, however, it is desirable to allow alon eri time for completion of the reaction descri e The foregoingdescribes but one embodiment of the method of securing a firm adherenceor a coating to an article. The invention is capable of many otherembodiments not mentioned above, and it is therefore desired that thescope of the invention be not limited except by the scope of theappended claims.

What is claimed is:

1. The method of securing the adhesion of a rubber compound to ametallic body which consists in depositing thereon a film of an acid ofthe organic class consisting of formic, acetic, oleic and palmiticacids, applying thereon the compound while in a plastic state, andthereafter vulcanizing the compound to the metallic body.

2. The method of insulating-an electrical conductor which consists indepositing thereon oleic acid to form a film, subsequently depositingupon the film a hydrocarbon compound containing sulphur, and thereaftervulcanizing the compound to the conductor= 3. The method of insulatingan electrical conductor which consists in wetting the conductor witholeic acid, depositing upon the acid covered conductor a rubber compoundwhile in a plastic state, and thereafter vulcanizing the compound to theconductor.

4. The method of securing the adhesion of a rubber compound to a tinnedmetallic body which consists in depositing thereon a quantity of oleicacid, applying the compound to said metallic body while in a plasticstate, and thereafter vulcanizing the compound to said metallic body.

In witness whereof, I hereunto subscribe my name this 28th day of May A.D., 1929.

THOMAS KING COX.

